In today's tutorial we'll matchmove the footage and use basic 3D geometry to create a severed leg, which can then be used as a matte to remove the original leg. The camera data can also be used to create a floor plane with some ground texture to clean up the original leg shadow. This plane will also be used to add ambient occlusion and fake blood. Be it a war zone or a zombie apocalypse, you never know when you might need to take off a leg. :)